The transition of a telecommunication operation network toward an IP-oriented network has been predominant along with development and applications of IP technologies, and the Ethernet, which acts as an optimal bearer mechanism for IP, has also been increasingly popular in the telecommunication operation network. Particularly, an access and aggregation network of the telecommunication operation network is typically based on information forwarding over a link layer, and therefore the Ethernet has been a dominant technology for an access and aggregation layer of the telecommunication operation network.
The Ethernet is widely applied in traditional enterprise networks due to its low bandwidth cost, simple management, and easy usage. These advantages are primarily based on the following basic Ethernet technical framework.
1. A Media Access Control (MAC) address: The MAC address is used to identify a terminal and is a forwarding and addressing mode based on flooding and MAC address auto-learning, and can be implemented without specific management and configuration.
2. Virtual Local Area Network (VLAN): The VLAN is a domain identifier for management, used to obtain a finer granularity management domain by reducing a broadcast domain, to implement inter-domain traffic isolation and control.
3. Topology and reliability: A tree-like topology is required to be logically maintained for flooding forwarding, and the tree-like topology is maintained and protected by the Spanning Tree Protocol/Rapid Spanning Tree Protocol (STP/RSTP).
4. Good support for multicast and broadcast.
The above basic technical framework is implemented primarily based on an Ethernet switching chip which is a core device for building an Ethernet apparatus.
FIG. 1 illustrates an Ethernet based Digital Subscriber Line (DSL) access and aggregation network system as defined by the DSL Forum. Likewise, the fiber based Fiber-to-the-X point (FTTx) and the World Interoperability for Microwave Access (WiMAX) have similar access systems except that the Access Node (AN) in FIG. 1 corresponds to an Optical Line Termination (OLT) of the FTTx and a Base Station (BS) of the WiMAX respectively. Their network systems are similar regardless of their different access technologies, and an access device is required to map an access bearer to an Ethernet bearer and traffic aggregation and forwarding is implemented based on Ethernet.
The AN and the Ethernet Aggregation of the access network constitute jointly a telecommunication access and aggregation network. Presently, these devices in the industry comply with the above-mentioned basic Ethernet technical framework and mostly are implemented with the existing Ethernet switching chip.
However, a telecommunication operation network, particularly the access and aggregation networks and telecommunication services, have their own inherent features as follows:
1. The access and aggregation networks are logically of a tree-like topology, instead of an all-switching structure, in a forwarding plane.
2. Logical connections isolated from each other from a user to a Broadband Network Gateway (BBNG) needs to be established.
3. Much attention is paid to management and control, and the management and control of users and data forwarding need to be implemented under the control of a service policy.
4. Much attention is paid to network security to prohibit MAC/IP address spoofing.
5. A Transparent LAN Service (TLS) for Ethernet message forwarding needs to be provided for a dedicated line access.
6. Scalability of the access and aggregation networks (MAC/VLAN) needs to be considered.
7. Efficient multicast from the BBNG to the users needs to be supported.
8. A higher QoS is required.
9. Capabilities of locating and identifying a user and a service needs to be provided.
10. Efficient management and capabilities of detecting and locating a failure needs to be provided for management and maintenance.
These requirements are in conflict with the basic Ethernet technical framework. Therefore, the Ethernet technical framework has to be improved in a telecommunication network context. The existing Ethernet technologies are described as follows.
A first prior art solution: a basic Ethernet forwarding and addressing mode is a solution based on flooding and auto-learning, and the solution includes that an Ethernet switching and forwarding engine creates a MAC address based forwarding table entry through flooding of an unknown/multicast/broadcast MAC address and auto-learning of the MAC address and ensures real time updating of a forwarding table and efficient usage of a forwarding table entry space through a MAC address aging mechanism. The solution with such a mechanism is disadvantageous in that: the MAC address belongs to a user terminal and thus is not trustworthy because numerous network attacks are made through MAC address spoofing, such as a Broadband Remote Access Server (BRAS) address spoofing, message redirecting, which may interfere greatly with a service of a normal user; the learning of the MAC address may consume a MAC address space table, which may result in a scalability problem of an aggregation layer device, for example, currently the aggregation layer device is required to be provided with a MAC address table entry space of at least 32K; and the MAC address table is vulnerable due to a Deny of Service (DoS) attack of the MAC address. Furthermore, the incredibility of the MAC address may also result in disability of identifying or locating a user according to the MAC address.
A second prior art solution: The Ethernet is based on the VLAN, thus obtaining a solution in which a finer granularity management domain is provided by reducing the broadcast domain and inter-domain traffic isolation and control are implemented. Particularly in the solution, since the Ethernet flooding mechanism may cause potential broadcast flooding and service traffic intercommunication between different users, the traditional Ethernet VLAN provides a finer granularity management domain through reducing the broadcast domain using a VLAN identifier and implements inter-domain traffic isolation and control for management and security; and due to the feature of the VLAN traffic isolation, and a field of 802.1p in a VLAN header identifier may be used to identify the priority of a message, the VLAN is typically used as an identifier of a service type in a telecommunication network. However this solution has the following drawbacks: the network security and service isolation cannot be achieved ideally with the existing VLAN technology, because the service intercommunication between users in a VLAN, which is typically prohibited in a telecommunication network, may be implemented with the flooding and MAC address auto-learning mechanism; furthermore, the MAC/IP spoofing still may be present in the VLAN; in addition, the problem of extendibility may occur in the case where the VLAN identifier is used as a service connection identifier between the AN and the BBNG primarily in that a service connection between the AN the BBNG is expected to carry physical location information of a user access port and the AN in addition to identifying a service type but the VLAN is provided with only a space of 4K.
A third prior art solution: a solution to maintaining and protecting a tree-like topology of Ethernet forwarding paths by means of the STP/RSTP is provided. Particularly in the solution, a tree-like topology has to be maintained logically for Ethernet forwarding mode of flooding, and the tree-like topology is maintained and protected by the STP/RSTP in the basic Ethernet technical framework; and a topology of service traffic between the AN and the BBNG in the access and aggregation network primarily includes a topology of point-to-point and point-to-multi-point from the BBNG to the AN, which is actually also a tree-like topology. This solution has the following drawbacks: the convergence of the link topology maintained by the STP/RSTP may be slow, even more in a network having an larger scale; in addition, according to a principle of protection switch, a mechanism at a lower layer has to be provided with more rapid protection switch, to ensure transparency to an upper-layer service; furthermore, the STP/RSTP provides protection according to a physical port or VLAN, but it is commonly required to a telecommunication service to implement end-to-end connection protection for a service connection, thus, the STP/RSTP is not applicable in a large telecommunication network.
A fourth prior art solution: a solution to implementing an Ethernet dedicated line service using Ethernet based on VLAN is provided. Particularly in the solution, a TLS is an important service type in a telecommunication network, and two Ethernet service modes of E-Line (point-to-point) and E-LAN (multi-point-to-multi-point) are further defined in the Metro Ethernet Forum (MEF). An important feature of the Ethernet dedicated line service is to enable user service transport transparency, and according to the traditional Ethernet VLAN technology, the Ethernet dedicated line service is typically identified by a VLAN identifier between the AN and the BBNG and is terminated at the BBNG. The Ethernet dedicated line service is identified and isolated from other services using the VLAN. This solution has the following drawbacks: a problem of transparency occurs in identifying the Ethernet dedicated line service based on a VLAN identifier, because the Ethernet dedicated line service requires all user messages to be transported transparently, but a layer-2 control message of the user, for example, a Bridge Protocol Data Unit (BPDU) message is based on specific multicast MAC encapsulation and cannot be encapsulated with the VLAN, and such message can not be forwarded through a network bridge in the standard Ethernet mechanism. However, such control message has to be forwarded transparently in order to provide the Ethernet dedicated line service in the telecommunication network.
Accordingly, problems occur in applying the existing basic Ethernet technical framework in the telecommunication operation network, particularly in the access and aggregation networks, and thus there is a need to improve the existing basic Ethernet technical framework.